Back bead control of the one-side robotic welding with visual sensor-cooperative control of current-waveform and torch motion for change of gap and welding position

Control of the weld pool in a first layer of the one-side multi-layer welding is important to obtain a good quality of the weld. For this purpose, the authors propose a new method, the switch back welding method, to get the stable back bead. In the forward stroke, the visual robot observes the groove shape and the root gap. In the backward process, it observes the surface of the weld pool every half cycle of the weaving to investigate whether the pulsed droplet is deposited to the root edge of the base metals and whether the deposited metal bridges the gap between the both base metals or not. The welding speed, the current waveform and the distance of the backward and forward stroke are obtained by using the fuzzy inference to get the stable and wide back bead